Axle and method of making same



July 11, 1939. J. H. FRlr-:DMAN l 2,165,472

AXLE AND METHOD OF MAKING SAME 2 Sheets-Sheet 1 l mvsmox mfp/VAN Filed Oct. 28, 1936 ATTORNEYS July 11, 1939- J. H. FRIEDMAN 2,165,472

AXLE AND METHOD 0F, MAKING SME Filed ocf. 2a, 19:56V 2 sheets-sheet 2 mvmon Jon/v H. Pie/EDMAN BY YW ATTORNEYS theaxle, To strengthen' the axleat thejouter' `ried out by a swaging operation upon the end above outlined swaging methodifails in use, it is Patented July 1l,

UNITED" silr-Esf;4 PATENT OFFICE l AxLnAND y -x'alssavz l ME'rnon oFMAxrNG SAME Johan. Friedman, Tlfnn, ohio, assigner to The National Machinery Company,

. corporation of Ohio Timm. Ohio, al

Application October 28,- i936, Serial No.-108,i)23

' sclaim's. (C1. zei-153.1).

This invention relates to axles, .axle forming apparatus and methods-of making axles and more particularly to an improved tubular type of rear axle, the apparatus and methods associated therewith.- j

The advantages of the tubular type of rear axle which flow from its strength per unit weight and low cost has resulted in a general acceptance of said type by the automotivetr-uck in- 'dustry. To shape the outer end of the tubular axle to iit the -rear wheel of the vehicle it'. is con.

ventional to taper the end of the axle and provide the tapered portion with a key seat to key the wheel to the axle, a bearing shoulder to support the axle in the axle housing and a threaded portion at'the outer end to retain the wheel on or Lwheel end thereof, it haslbeen proposed to thicken the tubular walls by tapering this portion of the axle. Ordinaiily the tapering is carof the axle after the same has been heated to a forging temperature. Thismethod, while effective to thicken the wallsfappears to adversely ail'ect the grain structure of that portion of the blank which is swaged. The swaging operation isa relatively slow, expensive operation andthe working in theswaging. dies tends to produce lamination:J or folds in'the meta-1 and produce areas of unequal hardness4 and unequal grain size. When van axle formed according to the found that usually .the failure is due to the fatigue of the metal and it is believed that this fatigue' is `accelerated bythe.numerous folds, laminations and unequal gr'aimsize caused by.

the swaging.

It isamong the objects of my invention to provide an axle of the tubular type having a reduced wheelattaching end and a method of making the same wherein the reduced portion of the axle will have improved grain structure characteristicsiand wherein the inethod will effect economies in manufacture over the prior art methods.

More specifically it is an object of my invention to provide a tubular axle having a reduced end wherein .the reduction is carried out by successive cold working and hot workingsteps so that the hot-working step will effectlan annealing action 'throughout the portion' of the tube previously cold worked, It is a further-:object of myA .invention to provide a method'of making a tnbular axle having a reduced end -portion wherein the reduction is effected by successive extrusion and upsetting operations.' It isafurther object vention.

Vshowing the axle blank as mille'd and Ithreade extruded portion'and upsetting the same. The

of my invention to provide a methodaccording to the preceding object' in which the extrusion is carried out cold and the upsetting iscarried out upon a `heated blank.- t is'aA further object of my invention to provide a 'tubular axle having [I] a reduced portion with thickened' walls which have grain structure characteristics resulting from successive cold extrusion and'ho't upsetting, It 'isa further object of my invention to provide a tubular axle with a reduced end p or- 10 tion with the greatest wall thickness at the juncture between the reduced end and the body of the axle.' Further objects and advantages relating to t-he 'novelty of the finished article and economies associated with the manufacture of'15 .sion step.

Figure 4 is a view similar to-.1igure 3 showing the blank resulting from a second extrusion step.

Figure 5 is a vieri1 similar to Figures 3 and 4 showing the blank 'following an upsetting step.

Figure 6 is a view similar t'o Figures 3 to 5 and ready for` assembly. l 85 T o avoid theA structural defects inherent in the prior art swaged tubular axle and the disadvantages associated withvthe prior art methods of forming tubular axles and to attain theobjects of my invention as outlined above I prefer to work vthe tubular blanktby first forcing the t end of saine through one or. more extrusion throats lwhile cold and thereafter heating vthe above operations may be conveniently carried' out on a conventional forging machine and I have shown in Figure lportions'of such a forging ma- A chine ha'vingstationai'y grippingdies, 'l and v8.

A complementary' group of movable gripping. dies (not shown) are adapted to cooperate with dies v. 6, 1." and 8 to securely grip the. tubularblank's during. the working thereof. T'o measure the extent of working'carried outan adjustable stop or gauge 8 is employed which is arranged to abut 2,165,47zff lto the inner end or unworked end of the tubular blank. A tubular blank such as I0 of Figure 2 is arranged in the gripping die 6 and projects beyond the forward face thereof in augment with an 'extrusion die II carried by the header slide I2 of the forging machine. The extrusion die II is provided with a restricted throat as at I3, and as the header slide moves forward toward the gripping dies the -extrusion die is forced over the projecting end of the blank I0. The rst'extrusion operation results in a blank indicated generally as Il in Figure 3, which is provided'with the reduced end portion I5.

In this connection I have found that a seamless tubular steel blank having a diameter of about S25/ggf' may be successfully reduced to have a diameter as at I5 of 3%6". Those skilled in the art, however, will understand that with the varioustypes of materials and machines available greater or lesser` reductions may be carried out by the method I have described. As will/be noted by comparison of Figures 2 and 3 the por- -tion of the blank which is reduced in the rst extrusion step is somewhat elongated by the extrusion and the walls thereof are thickened. Referring again to the proportions mentioned above by way of example I nd that the wall thickness during the first extrusion is increased from about 2%4 to about 1%2".

Following the first extrusion step the resultant blank I4 is moved to a lower blank gripping sectionl at 'I of the gripping dies. The blank may be adjusted at its inner end by abutment with a gauge 29.as in the first instance and a second header slide die I6 is forced over the projecting end of the blank I4. The die I6 is provided with an extrusion throat I1 having a lesser diameter than that of the extrusion die I I. The reduction in diameter on the blank and the elongation of the blank effected by the second extrusion step is indicated in the blank I8 in Figure 4. Referring again to the specific example given in connection with this description of my method I find that the wall thickness during the second extrusion is in creased from @bout 1%2" to about 1/2". .In the second extrusion step a more gradual taper is formed by the entrance to the extrusion die I6 and the diameter is reduced from about 3%6 to Following the working of the blank by extrusion which is carried out cold so that extrusion lubricants may be employed and so as to improve the grain'structure of the extruded portion, the outer end of the blank is heated by any suitable means to a forging temperature. then transferred to a third gripping section 8 in the gripping dies, which section is in alignment with an upsetting tool 20 carried by the header slide. While at 'this Work station the blank is adjusted by gauge I9. The upsetting tool is preferably provided with a mandrel 2| arranged to project within the extruded t'ubular portion of the blank and the annular face 22 abuts the end of the blank I8. As the header slide moves forward the heated end of the blank I8 is upset by anvil face 22, and acquires the proportions illustrated by blank 23 in Figure 5. The upsetting operation thickens the walls further and reduces the length of the portion heretofore extruded. This operation results in the production of a wheel attaching portion about 21%, in diameter having a Wall thickness of about 5/8" where carried out on a blank according to the example.

The greatest thickening of the tube wall results at 24, the juncture between the largest diameter The blank isof the tube and the reduced or wheel attaching portion of the tube. This provides an amount of metal which will safely permit the milling of the outer bearing shoulder 25 of the axle. It will be understood that the portion of the axle projecting beyond the bearing shoulder functions as a can'- tilever beam and that the maximum stress in the metal occurs at this point. The heating of the end of the blank to facilitate the upsetting anneals that portion of the blank which has heretofore been cold worked and the result is a tubular axle with a reduced end portion having uniform grain size throughout, free of laminations or folds and with walls adequately .thickened to resist the stresses imposed thereon. y

Following the extrusion and upsetting operations above described the axle blank is milled as shown in Figure 8 and is provided with a threaded i `extremity as at 26, a key seat at 21 and an annui lar bearing shoulder 25. The thickening of the walls provides ample material to permit safe milling of the key seat 2l. It will be understood that the extrusion, upsetting and annealing as provided by my method will result in a key seat 21 wherein the metal of the seat is hard, of uniform grain size throughout, free of laminations and .Y

' therefore less subject to failure by shearing out the key seat than theprior art structures.

Although I have described my invention in connection with a rear axle for a vehicle those skilled in the art will appreciate that the method is well suited to the formation of other articles such as, for instance, pipe joints, and that although I have described a preferred method of carrying out my invention in considerable detail,

I do not wish to be limited to the precise axle crease in the diameter and an increase in wall thickness.

2. A tubular axle comprising a main body portion and an extruded and upset end portion, a lengthpf the wall of said end portion immediately adjacent said body provided with a taper having a progressive outside diameter reductiomtoward the en'd of the axle, the interior of said end .portion having a progressively decreasing diameter towards the main bodyof the blank through the same length whereby the maximum wall'thickness is provided at the juncture between the main body portion and the extruded upset end.

3. That method of forming a tubular rearaxle Whichjcomprises extruding a portion of the length of a tubular blank while cold, heating said extruded portion, confining the walls of said heated extruded blank between a mandrel and a die and upsetting the extruded and heated portion of the blank into the confines of the die and against said mandrel to increase the outer diameter and reduce' the inner diameter of said extruded and heated end portion.

4. The method of making a tubular axle comprising extruding the end portion of a tubular metal blank while cold to 'form an end portion of reduced diameter joined to the main body of the blank by a tapered portion, and thereafter heating and upsetting the reduced end portion and the tapered portion so as to work the metal of the tapered portion and increase the wall thickness thereof.

. 5. A tubular metal axle comprising a main body portion and a cold extruded and hot upset reduced end portion integrally joined to the body portion by an upset tapered portion, said taperedl portion having a wall of substantially greater thickness than either the body portion or the' reduced end portion, and said reduced end portion having a grain structure characteristic of that produced by rst cold extruding and there- 

